Turbine seal system

ABSTRACT

A system includes a multi-stage turbine. The multi-stage turbine includes a first turbine stage including a first wheel having a plurality of first blade segments spaced circumferentially about the first wheel, a second turbine stage including a second wheel having a plurality of second blade segments spaced circumferentially about the second wheel, and an interstage seal extending axially between the first and second turbine stages. The interstage seal is configured to be installed or removed while the first and second wheels remain in place in the respective first and second turbine stages.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to gas turbines, and morespecifically, to seals within turbines.

In general, gas turbine engines combust a mixture of compressed air andfuel to produce hot combustion gases. The combustion gases may flowthrough one or more turbine stages to generate power for a load and/orcompressor. A pressure drop may occur between stages, which may allowleakage flow of a fluid, such as combustion gases, through unintendedpaths. Seals may be disposed between the stages to reduce fluid leakagebetween stages. Unfortunately, the seals may be subject to stresses,such as thermal stresses, which may bias the seals in axial and/orradial directions thereby reducing effectiveness of the seals. Forexample, seal deflection may increase the possibility of a rub conditionbetween stationary and rotating components.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a multi-stage turbine. Themulti-stage turbine includes a first turbine stage including a firstwheel having a plurality of first blade segments spacedcircumferentially about the first wheel, a second turbine stageincluding a second wheel having a plurality of second blade segmentsspaced circumferentially about the second wheel, and an interstage sealextending axially between the first and second turbine stages. Theinterstage seal is configured to be installed or removed while the firstand second wheels remain in place in the respective first and secondturbine stages.

In a second embodiment, a system includes an interstage turbine sealconfigured to mount axially between first and second turbine stages of amulti-stage turbine. The interstage turbine seal includes an inclinedsupport rib configured to enable the interstage seal to pivot toward andaway from an axial axis of the multi-stage turbine without removal of afirst wheel of the first turbine stage and a second wheel of the secondturbine stage.

In a third embodiment, a method includes positioning a first recessedportion of an interstage seal about a first wheel rim of a turbomachine,pivoting a second recessed portion of the interstage seal toward anaxial axis of the turbomachine, and moving the interstage seal along theaxial axis toward a second wheel rim of the turbomachine to position thesecond recessed portion about the second wheel rim.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic flow diagram of an embodiment of a gas turbineengine that may employ turbine seals;

FIG. 2 is a cross-sectional side view of an embodiment of the gasturbine engine of FIG. 1 taken along the longitudinal axis;

FIG. 3 is a partial cross-sectional side view of the gas turbine engineof FIG. 2 illustrating an embodiment of a seal structure between turbinestages;

FIG. 4 is a partial cross-sectional side view of the gas turbine engineof FIG. 2 illustrating an embodiment of a seal structure being pivotedbetween adjacent stages;

FIG. 5 is a partial cross-sectional side view of the gas turbine engineof FIG. 2 illustrating an embodiment of a seal structure being movedalong the longitudinal axis between adjacent stages;

FIG. 6 is a partial cross-sectional side view of the gas turbine engineof FIG. 2 illustrating an embodiment of a seal structure being installedbetween adjacent stages;

FIG. 7 is a front perspective view of an embodiment of a seal structure;

FIG. 8 is a rear perspective view of an embodiment of a seal structure;

FIG. 9 is a front view of an embodiment of a seal structure; and

FIG. 10 is a side view of an embodiment of a seal structure.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The present disclosure is directed to gas turbine engines that includeinterstage seals, wherein each interstage seal includes features to sealan interstage gap without the use of additional components, such asspacer wheels. Thus, gas turbine engines that include such interstageseals may be less costly than engines using spacer wheels. For example,the gas turbine engine may include a first turbine stage that includes afirst wheel that has a plurality of first blade segments spacedcircumferentially about the first wheel, and a second turbine stage thatincludes a second wheel having a plurality of second blade segmentsspaced circumferentially about the second wheel. The interstage seal mayextend axially between the first and second turbine stages to seal theinterstage gap. In addition, embodiments of the interstage seal may beinstalled and removed without disassembling a rotor of the gas turbineengine. For example, the interstage seal may be configured to beinstalled or removed while the first and second wheels remain in placein the respective first and second turbine stages. Thus, if only theinterstage seal is replaced, the rotor of the gas turbine engine neednot be disturbed, thereby potentially reducing maintenance time,complexity, and/or cost. In further embodiments, the interstage seal mayinclude an inclined support rib that is configured to enable theinterstage seal to pivot toward and away from an axial axis of the gasturbine engine without removal of the first wheel or the second wheel.In other words, pivoting of the interstage seal may enable theinterstage seal to be replaced without disturbing the rotor assembly. Inother embodiments, a recessed portion of the interstage seal may beconfigured to enable the pivoting of the interstage seal.

FIG. 1 is a block diagram of an exemplary system 10 including a gasturbine engine 12 that may employ interstage seals configured to beinstalled or removed without rotor disassembly, as described in detailbelow. In certain embodiments, the system 10 may include an aircraft, awatercraft, a locomotive, a power generation system, or combinationsthereof. The illustrated gas turbine engine 12 includes an air intakesection 16, a compressor 18, a combustor section 20, a turbine 22, andan exhaust section 24. The turbine 22 is coupled to the compressor 18via a shaft 26.

As indicated by the arrows, air may enter the gas turbine engine 12through the intake section 16 and flow into the compressor 18, whichcompresses the air prior to entry into the combustor section 20. Theillustrated combustor section 20 includes a combustor housing 28disposed concentrically or annularly about the shaft 26 between thecompressor 18 and the turbine 22. The compressed air from the compressor18 enters combustors 30, where the compressed air may mix and combustwith fuel within the combustors 30 to drive the turbine 22.

From the combustor section 20, the hot combustion gases flow through theturbine 22, driving the compressor 18 via the shaft 26. For example, thecombustion gases may apply motive forces to turbine rotor blades withinthe turbine 22 to rotate the shaft 26. After flowing through the turbine22, the hot combustion gases may exit the gas turbine engine 12 throughthe exhaust section 24. As discussed below, the turbine 22 may include aplurality of interstage seals, which may be installed or removed whilerotating components of the turbine 22, such as wheels, remain in place.Thus, maintenance affecting the interstage seals may be performedwithout complete disassembly of the turbine 22.

FIG. 2 is a cross-sectional side view of an embodiment of the gasturbine engine 12 of FIG. 1 taken along the longitudinal axis 32. Asdepicted, the gas turbine 22 includes three separate stages 34. Eachstage 34 includes a set of blades 36 coupled to a rotor wheel 38 thatmay be rotatably attached to the shaft 26 (FIG. 1). The blades 36 extendradially outward from the rotor wheels 38 and are partially disposedwithin the path of the hot combustion gases. Seals 40 extend between andare supported by adjacent rotor wheels 38. As discussed below, the seals40 may include recessed portions that fit about adjacent wheels 38 forsupport. The recessed portions may be configured to enable the seals 40to pivot toward and away from the longitudinal axis 32 duringinstallation or removal. Thus, the seals 40 may be installed or removedwhile the rotor wheels 38 remain in place in the gas turbine engine 12.In addition, the seals 40 may provide for improved cooling of the stages34. Although the gas turbine 22 is illustrated as a three-stage turbine,the seals 40 described herein may be employed in any suitable type ofturbine with any number of stages and shafts. For example, the seals 40may be included in a single stage gas turbine, in a dual turbine systemthat includes a low-pressure turbine and a high-pressure turbine, or ina steam turbine. Further, the seals 40 described herein may also beemployed in a rotary compressor, such as the compressor 18 illustratedin FIG. 1. The seals 40 may be made from various high-temperaturealloys, such as, but not limited to, nickel based alloys.

As described above with respect to FIG. 1, air enters through the airintake section 16 and is compressed by the compressor 18. The compressedair from the compressor 18 is then directed into the combustor section20 where the compressed air is mixed with fuel. The mixture ofcompressed air and fuel is generally burned within the combustor section20 to generate high-temperature, high-pressure combustion gases, whichare used to generate torque within the turbine 22. Specifically, thecombustion gases apply motive forces to the blades 36 to turn the wheels38. In certain embodiments, a pressure drop may occur at each stage 34of the turbine 22, which may allow gas leakage flow through unintendedpaths. For example, the hot combustion gases may leak into theinterstage volume between turbine wheels 38, which may place thermalstresses on the turbine components. In certain embodiments, theinterstage volume may be cooled by discharge air bled from thecompressor or provided by another source. However, flow of hotcombustion gases into the interstage volume may abate the coolingeffects. Accordingly, the seals 40 may be disposed between adjacentwheels 38 to seal and enclose the interstage volume from the hotcombustion gases. In addition, the seals 40 may be configured to directa cooling fluid to the interstage volume or from the interstage volumetoward the blades 36.

FIG. 3 is a cross-sectional side view of an embodiment of a pair ofadjacent rotor stages 34 shown in FIG. 2. In the following discussion,reference may be made to an axial direction or axis 50, a radialdirection or axis 52, and a circumferential direction or axis 54,relative to the longitudinal axis 32 of the gas turbine engine 12. Hotfluids, such as hot combustion gases or steam, with a flow path 56(illustrated generally by an arrow) enters at an upstream side 58 andexits at a downstream side 60. For illustrative purposes, only a portionof the stages 34 are illustrated in FIG. 3. Specifically, a firstturbine stage 62 is shown near the upstream side 58 and a second turbinestage 64 is shown near the downstream side 60. The first turbine stage62 includes a first wheel 66 with a plurality of first blade segments 68extending radially outward 52 from a first wheel post portion 70 of thefirst wheel 66. The first wheel post portion 70 is disposed along thecircumference of the first wheel 66 and includes slots 72 (e.g., axialdovetail slots) for retaining lower segments (e.g., axial dovetail tabs73) of the first blade segments 68. Similarly, the second turbine stage64 includes a second wheel 74 with a plurality of second blade segments76 extending radially outward 52 from a second wheel post portion 78 ofthe second wheel 74. The second wheel post portion 78 is disposed alongthe circumference of the second wheel 74 and includes slots 80 (e.g.,axial dovetail slots) for retaining lower segments (e.g., axial dovetailtabs 81) of the plurality of second blade segments 76. In certainembodiments, approximately 50 to 150 first and second blade segments 68and 76 may be mounted and spaced circumferentially 54 around the firstand second wheels 66 and 74 and a corresponding axis of rotation(extending generally in the direction indicated by arrow 50). In furtherembodiments, methods other than the slots and tabs described above maybe used to couple the first and second blade segments 68 and 76 to thefirst and second wheels 66 and 74.

The interstage seal 40 extends between the first and second adjacentwheels 66 and 74 and is mechanically supported by the first and secondturbine stages 62 and 64. As described in detail below, an annularinterstage seal assembly 41 (as shown in FIG. 9) may include a pluralityof interstage seal segments 40 disposed about the longitudinal axis 32of the gas turbine engine 12. In other words, the interstage sealassembly 41 is a segmented annular seal assembly. The interstage sealsegment 40 includes an outer bridge portion 82, or axial beam, disposednear the first and second pluralities of blade segments 68 and 76. Theouter bridge portion 82 is a structure that provides support for theinterstage seal 40. The interstage seal segment 40 also includes aninner bridge portion 84 disposed near the first and second wheels 66 and74. The inner bridge portion 84 also provides support for the innerstage seal 40. In addition, the inner bridge portion 84 may have acatenary shape, e.g., a curved annular shape, configured to provideadditional strength to the interstage seal 40. At intermediate locationsbetween the outer bridge portion 82 and the inner bridge portion 84, theinterstage seal 40 includes one or more intermediate supports 86, orradial beams, which provide support for the inner stage seal 40 in theradial direction 52. As illustrated in FIG. 3, the intermediate supports86 may be generally aligned with the radial direction 52. In otherembodiments, the interstage seal 40 may include three, four, five, six,or more intermediate supports 86. The intermediate supports 86 may bedisc-shaped structures that generally taper in the radial direction 52.In other words, the intermediate supports 86 may be thicker near theinner bridge portion 84 than near the outer bridge portion 82.

The interstage seal 40 may also include an inclined support rib 88, orsupport beam, that may be disposed between the inner and outer bridgeportions 82 and 84. As shown in FIG. 3, the inclined support rib 88 maybe inclined with respect to the radial direction 52. The interstage seal40 may also include an optional inclined support portion 90 to provideadditional support for the portion of the outer bridge portion 82 notsupported by the inclined support rib 88. In certain embodiments, theinclined support portion 90 may be omitted. In further embodiments, theinclined support portion 90 may have a generally triangular crosssectional shape. Because the inclined support rib 88 may be inclinedwith respect to the radial direction 52, the inclined support rib 88 mayform an outer angle 92 with the outer bridge portion 82 and an innerangle 94 with the inner bridge portion 84. As shown in FIG. 3, the outerand inner angles 92 and 94 may be acute angles of less thanapproximately 90 degrees. For example, in certain embodiments, the outerand inner angles 92 and 94 may be between approximately 10 to 80degrees, 20 to 70 degrees, 30 to 60 degrees, or 40 to 50 degrees. In oneembodiment, the outer and inner angles 92 and 94 may be less thanapproximately 75 degrees. As discussed in detail below, the inclinedsupport rib 88 enables the interstage seal 40 to be pivoted duringinstallation and removal from the gas turbine engine 10. Thus, theinterstage seal 40 may be installed or removed without removal of thefirst and second wheels 66 and 74. In addition, in certain embodiments,the interstage support portion 90 may be coupled to the inner bridgeportion 84 instead of the outer bridge portion 82.

Seal cavities 96 may be formed in the interstage seal 40 between theintermediate supports 86. The seal cavities 96 may enable a coolingfluid, such as air, to circulate between the first and second turbinestages 62 and 64 as discussed in detail below. Recessed portions 98 maybe formed between the outer and inner bridge portions 82 and 84 near theends of the interstage seal 40 facing toward the first and secondturbine stages 62 and 64. Specifically, the intermediate supports 86 andthe inclined support rib 88 may not be located at the ends of the outerand inner bridge portions 82 and 84. Thus, the recessed portions 98 areformed in the spaces surrounded by the intermediate supports 86, theinclined support rib 88, and the outer and inner bridge portions 82 and84. The seal cavities 96 may have a variety of cross sectional shapesdepending on the configuration of the intermediate supports 86 and theinclined support rib 88. For example, the seal cavities 96 may haverectangular, square, triangular, circular, oval, or other suitable crosssectional shapes. Similarly, the recessed portions 98 may have a varietyof cross sectional shapes, such as, but not limited to, rectangular,square, triangular, circular, oval, or other suitable shapes. Inaddition, the inclined support portion 90 may occupy part of therecessed portion 98 adjacent to the inclined support rib 88. In otherembodiments, the inclined support portion 90 may be omitted. Asdiscussed in detail below, the recessed portions 98 may at leastpartially fit over portions of the first and second turbine stages 62and 64. In other words, portions of the first and second wheels 66 and74 may extend into the recessed portions 98 to enable pivoted motion ofthe interstage seal 40 and/or enable installation and removal ofinterstage seal 40 without removal of the first and second wheels 66 and74.

In certain embodiments, a labyrinth seal 100 may be disposed adjacent tothe interstage seal 40 and between the first and second turbine stages62 and 64. The labyrinth seal 100 may be configured to help block axialleakage of the hot combustion gases 56. For example, the labyrinth seal100 may include an abradable coating 102 on the surface facing towardthe interstage seal 40. Correspondingly, the interstage seal 40 mayinclude one or more teeth 104 disposed adjacent to the abradable coating102. During operation of the gas turbine engine 10, the teeth 104 may bein close proximity to the abradable coating 102 to help block axialleakage of the hot combustion gases 56 between the first and secondturbine stages 62 and 64. In response to transient conditions, such asrotor transients, the abradable coating 102 may be configured topartially abrade when in contact with the teeth 104 to help preventdamage to the teeth 104. In other words, the abradable coating 102 maybe softer than the teeth 104. In further embodiments, seals other thanthe labyrinth seal 100 may be used together with the interstage seal 40.

The portions of the outer bridge portion 82 that extends past theintermediate support 86 and the inclined support rib 88 may be referredto as end portions. Specifically, the outer bridge portion 82 mayinclude a first end portion 106 and a second end portion 108. In certainembodiments, the first and second end portions 106 and 108 may includeoptional centrifugal seals 110 to help block radial leakage of the hotcombustion gases 56. For example, the first and second end portions 106and 108 may include a recessed slot 111 to engage with the centrifugalseal 110. The seal 110 may include a support rod 112, a curved supportpiece 114, and a seal rod 116. The support rod 112 of the centrifugalseal 110 may fit in the recessed slot 111. The curved support piece 114may be attached to the support rod 112. Finally, the seal rod 116 may beattached to the end of the curved support piece 114. When the gasturbine engine 10 is operating, centrifugal forces may cause the sealrod 116 to move away from the interstage seal 40 and toward the surfacesof the first and second turbine stages 62 and 64 facing the interstageseal 40. Thus, the seal rod 116 may be in contact with the first andsecond blade segments 68 and 76 during operation of the gas turbineengine 10 to help block radial leakage of the hot combustion gases 56.To accommodate the movement of the centrifugal seals 110 duringoperation of the gas turbine engine 10, small gaps exist between thefirst and second end portions 106 and 108 of the interstage seal 40 andthe first and second turbines stages 62 and 64. By moving toward or awayfrom the interstage seal 40, the centrifugal seals 110 may be able tomaintain contact with the first and second turbine stages 62 and 64 evenduring axial transients that may cause the gaps to increase or decreaseduring operation of the gas turbine engine 10. In other embodiments, thecentrifugal seals 110 may be omitted or seals other than the centrifugalseals 110 may be used at the outer bridge portion 82 to provide forradial sealing.

In certain embodiments, the second end portion 108 may include a firstsupport feature 118 configured to engage with a second support feature120 disposed on one or more of the second blade segments 76. Forexample, the first support feature 118 may be a female alignment portion(e.g., a notch) and the second support feature 120 may be a malealignment portion (e.g., a tab). In other embodiments, the first supportfeature 118 may be the male alignment portion, and the second supportfeature 120 may be the female alignment portion. Together, the first andsecond support features 118 and 120 may help to block radial movement ofthe interstage seal 40 in the direction 52 toward the axial axis 50 ofthe gas turbine engine 10 during installation or removal of theinterstage seal 40. In addition, the first and second support features118 and 120 may help to block circumferential movement of the interstageseal 40 in the direction 54 during operation of the gas turbine engine10. Use of the first and second support features 118 and 120 duringinstallation and removal of the interstage seal 40 is described indetail below.

The inner bridge portion 84 may also include end portions, specifically,a first end portion 124, and a second end portion 126. The first endportion 124 may be configured to engage with a first wheel rim 128 ofthe first wheel 66 during operation of the gas turbine engine 10.Specifically, during operation of the gas turbine engine 10, centrifugalforces may move the interstage seal 40 in the radial direction 52 towardthe first rim 128. Contact between the first end portion 124 and thefirst rim 128 may provide an additional seal against radial leakage ofthe hot combustion gases 56. The first end portion 124 may include anaxial stop 130 disposed in the recessed portion 98. The axial stop 130may be a structure configured to restrict movement of the interstageseal 40 in the axial direction 50 toward the first turbine stage 62.Similarly, the second end portion 126 may be configured to engage with asecond wheel rim 132 of the second wheel 74 during operation of the gasturbine engine 10. Contact of the second end portion 126 and the secondrim 132 may help block radial leakage of the hot combustion gases 56.Lengths 125 and 127 of the first and second end portions 124 and 126 maybe selected to provide sufficient crush stress and clearance forassembly and removal for the interstage seal 40 depending on theselected materials. For example, the lengths 125 and 127 may be betweenapproximately 5 mm to 50 mm, 10 mm to 25 mm, or 15 mm to 20 mm. Each ofthe lengths 125 and 127 may be between approximately 5 percent to 40percent, 10 percent to 25 percent, or 15 percent to 20 percent of anoverall length 136 of the interstage seal 40.

In the illustrated embodiment, the interstage seal assembly 41, of whichthe interstage seal 40 is one segment of the assembly 41, is annularlydisposed (in the circumferential direction 54) between the first andsecond wheels 66 and 74. Thus, the first and second wheels 66 and 74form annular structures with the interstage seal assembly 41 extendingas an annular structure between the first and second wheels 66 and 74.During operation, the first and second wheels 66 and 74 and theinterstage seal assembly 41 rotate about a common axis. The interstageseal assembly 41 may include a 360-degree segmented (e.g., 2 to 100segments) circular structure that attaches to adjacent first and secondwheels 66 and 74 to form a wall that thermally isolates an interstagevolume or wheel cavity 134 that forms an air-cooling chamber.

FIGS. 4-6 illustrated various steps that may be performed duringinstallation of the interstage seal 40. Removal of the interstage seal40 may be accomplished by performing these steps in reverse. Startingwith the first step, FIG. 4 illustrates a partial cross sectional sideview of the interstage seal 40 being pivoted between the first andsecond turbine stages 62 and 64. As shown in FIG. 4, the second bladesegments 76 have been removed to facilitate the installation of theinterstage seal 40. The first blade segments 68 remain in place in thefirst stage 62. In other embodiments, the interstage seal 40 may beinstalled by removing the first blade segments 68, with the second bladesegments 76 remaining in place in the second stage 64. Thus,installation of the interstage seal 40 may not involve removal of boththe first and second blade segments 68 and 76, thereby substantiallysimplifying the installation or removal of the interstage seal 40.Moreover, as shown in FIG. 4, the first and second wheels 66 and 74remain in place during installation (and removal) of the interstage seal40, thereby substantially simplifying the installation or removal of theinterstage seal 40. During installation of the interstage seal 40, thesecond end portion 126 is positioned, or hooked, under the second rim132. Specifically, a corner 148 formed between the inclined support rib88 and the inner bridge portion 84 is placed adjacent to, in anoverlapping relationship with, the second wheel rim 132. In other words,an overlap 149 of the corner 148 and the second rim 132 exists in theaxial 50 and radial 52 directions. As a result, the interstage seal 40may be pivoted, or rotated, about the corner 148 in the direction of thearrow 150 toward the axial axis 50. As shown in FIG. 4, an outer edge151 of the first end portion 124 may follow an arc 152 as the interstageseal 40 is moved in the direction 150. Thus, the overlap 149 providessufficient clearance to enable the outer edge 151 to clear the firstwheel rim 128 as the interstage seal 40 pivots toward the axial axis 50.At the beginning of the installation process, the inclined support rib88 may be substantially parallel to a face 153 of the second wheel postportion 78. The configuration of the inclined support rib 88 and therecessed portion 90 enables the overlap 149 to be greater, therebyenabling the outer edge 151 to clear the first wheel rim 128 asindicated by the dashed line 152. In addition, the inclined supportportion 90 may overlap a portion 154 of the second wheel support post 78when viewed cross-sectionally. As described in detail below, two or moreinclined support portions 90 may surround the second wheel support post78. As the installation of the interstage seal 40 proceeds, the firstend portion 124 rotates toward the first wheel rim 128 and the inclinedsupport rib 88 moves away from the second wheel support post 78.

FIG. 5 is a partial cross-sectional side view of the interstage seal 40being moved along the axial axis 50. As shown in FIG. 5, the interstageseal 40 has been rotated such that the first end portion 124 may bemoved under the first wheel rim 128 as indicated by arrow 170. Inaddition, the second end portion 126 may remain overlapping with thesecond wheel rim 132. Specifically, the corner 148 may be adjacent tothe second wheel rim 132. The overlap 149 enables the first end portion124 to move under the first wheel rim 128 while the overlap 149 ismaintained between the second end portion 126 and the second wheel rim132. As the interstage seal 40 is moved in the direction of arrow 170,the axial stop 130 may contact the first wheel rim 128 to block furtheraxial movement 50 of the interstage seal 40. In addition, the corner 148moves at least partially away from the second wheel rim 132.

FIG. 6 is a partial cross-sectional side view of the interstage seal 40illustrating the completion of the installation process. As shown inFIG. 6, the axial stop 130 is adjacent to the first wheel rim 128, andthe corner 148 has moved away from the second wheel rim 132. The firstend portion 124 remains axially 50 overlapped with the first wheel rim128 and the second end portion 126 remains axially 50 overlapped withthe second wheel rim 132. In addition, the second blade segment 76 maybe moved in the direction of arrow 180 toward the interstage seal 40.Specifically, the second support feature 120 may be engaged with thefirst support feature 118. Once the first and second support features118 and 120 are engaged, the interstage seal 40 may be blocked frommoving toward or away from the axial axis 50 of the gas turbine engine10. Thus, the interstage seal 40 may be self-supporting throughout therest of the installation process without having to hold or restrain theinterstage seal 40 from moving. Finally, the labyrinth seal 100 may bemoved in the direction of arrow 182 toward the interstage seal 40. Incertain embodiments, the labyrinth seal 100 may be coupled to the caseof the gas turbine engine 10 and thus, the labyrinth seal 100 may beinstalled when the case of the gas turbine engine 10 is mounted. Afterthe gas turbine engine 10 starts, the centrifugal seals 110 (if used)may move outward to radially seal the gaps between the interstage seal40 and the first and second turbine stages 62 and 64.

FIG. 7 is a front perspective view of an embodiment of one interstageseal segment 40 of the interstage seal assembly 41. As shown in FIG. 7,the axial stop 130 includes a first face 200 and a second face 202. Thefirst face 200 may face toward the first turbine stage 62 and the secondface 202 may face toward the interstage seal 40. In certain embodiments,the first face 200 may be generally flat to correspond to the firstwheel 66. In addition, the second face 202 may be curved to provide agreater support for attachment of the axial stop 130 to the first endportion 124. In other embodiments, the second face 202 may be flat. Inaddition, the axial stop 130 may have a width 204 that is approximatelythe same as a width of the interstage seal segment 40. Further, theaxial stop 130 may be defined by a height 206, which may be selected toprovide sufficient surface area for the axial stop 130 to help blockundesired axial movement of the interstage seal 40.

FIG. 8 is a rear perspective view of an embodiment of one interstageseal segment 40 of the interstage seal assembly 41. As shown in FIG. 8,the interstage seal 40 includes two inclined support portions 90.Specifically, the two interstage support portions 90 are located onouter sides 218 of the interstage seal 40. Thus, an interstage supportportion gap 220 exists between the two inclined support portions 90.During installation or removal of the interstage seal 40, the secondwheel support post 78 may fit into the interstage support portion gap220. Thus, the interstage seal 40 may be pivoted about the second wheelsupport post 78 during installation or removal of the interstage seal40. By pivoting about the second wheel support post 78, the second stage64 may remain in place during maintenance of the interstage seal 40. Inthe illustrated embodiment, each of the inclined support portions 90 isdefined by a width 222. Together, the widths 222 of the inclined supportportions 90 and the interstage support portion gap 220 may beapproximately the same as the width 204 of the interstage seal 40. Inaddition, the inclined support portions 90 may be defined by a height224. As shown in FIG. 8, the height 224 is less than a height of theinterstage seal 40. In other embodiments, the height 224 may be smalleror greater depending on the amount of incline of the inclined supportrib 88 and the support desired for the outer bridge portion 82. Forexample, if the angle 94 is smaller, the inclined support portions 90may have greater heights 224 to provide additional support for the outerbridge portion 82. In other embodiments, only one inclined supportportion 90 may be provided near the center of the interstage seal 40. Infurther embodiments, the interstage seal 40 may include more than twoinclined support portions 90. Some embodiments may omit the inclinedsupport portion 90.

FIG. 9 is a front view of three adjacent interstage seals 40 of thesegmented interstage seal assembly 41. The assembly 41 may include aplurality of interstage seals 40, such as 2 to 100 seals 40, disposedadjacent to one another to form a complete 360-degree ring about thelongitudinal axis 32 of the gas turbine engine 10. As shown in FIG. 9,each of the interstage seals 40 is arcuate in the circumferentialdirection 54. The assembly 41 of the interstage seals 40 may includeouter seals 240 and inner seals 242. Axial slots 246 may be formed inthe outer and inner bridge portions 82 and 84 to accommodate the outerand inner axial seals 240 and 242. In other words, the outer and innerseals 240 and 242 extend in the axial direction 50 along the axial slots246. Outer and inner seals 240 and 242 may be installed between each ofthe interstage seals 40 of the interstage seal assembly 41 as discussedabove. The outer and inner axial seals 240 and 242 may help to blockradial leakage of the hot combustible gases 56.

FIG. 10 is a side view of an embodiment of the interstage seal 40. Asshown in FIG. 10, the outer and inner seals 240 and 242 are disposed inaxial slots 246 that run along the outer and inner bridge portions 82and 84. In addition, the interstage seal 40 may include one or morecooling passages 260 to enable the cooling fluid to flow toward thefirst and second blade segments 68 and 76. For example, in certainembodiments, the cooling passages 260 may enable the cooling fluid toflow from the interstage volume 134 toward the first and second bladesegments 68 and 76. In other embodiments, the cooling fluid may flowfrom a casing structure of the gas turbine engine 10 into the first andsecond blade segments 68 and 76 through the cooling passages 260. Thecooling passages 260 may be formed in the outer and inner bridgeportions 82 and 84, the intermediate support beams 86, and/or theinclined support rib 88. The cooling passages 260 formed in the outerand inner bridge portions 82 and 84 may enable the cooling fluid to flowfrom the interstage volume 134 or the casing structure to the first andsecond blade segments 68 and 76. The cooling passages 260 formed in theintermediate support beams 86 and/or the inclined support rib 88 mayenable the cooling fluid to flow between the recessed portions 98 andthe seal cavities 96.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A system, comprising: a multi-stage turbine, comprising: a firstturbine stage comprising a first wheel having a plurality of first bladesegments spaced circumferentially about the first wheel; a secondturbine stage comprising a second wheel having a plurality of secondblade segments spaced circumferentially about the second wheel; and aninterstage seal extending axially between the first and second turbinestages, wherein the interstage seal is configured to be installed orremoved while the first and second wheels remain in place in therespective first and second turbine stages.
 2. The system of claim 1,wherein each of the plurality of first blade segments is coupled to thefirst wheel using a plurality of first mounts, and each of the pluralityof second blade segments is coupled to the second wheel using aplurality of second mounts.
 3. The system of claim 2, wherein each firstmount comprises a first slot in the first wheel and a first tab in oneof the first plurality of blade segments, and each second mountcompromises a second slot in the second wheel and a second tab in one ofthe second plurality of blade segments.
 4. The system of claim 1,wherein the interstage seal is configured to pivot toward an axial axisof the multi-stage turbine during installation of the interstage seal,and the interstage seal is configured to pivot away from the axial axisof the multi-stage turbine during removal of the interstage seal.
 5. Thesystem of claim 1, wherein the interstage seal comprises an inclinedsupport rib at an angle from an inner bridge portion of the interstageseal, wherein the inclined support rib enables the interstage seal topivot toward and away from an axial axis of the multi-stage turbine. 6.The system of claim 5, wherein the interstage seal comprises a secondrecessed portion adjacent to the inclined support rib, the secondrecessed portion is configured to receive a second portion of the secondwheel to enable pivotal motion of the interstage seal toward and awayfrom the axial axis, and a first recessed portion of the interstage sealis configured to receive a first portion of the first wheel while theinterstage seal is moved along the axial axis toward the first turbinestage.
 7. The system of claim 5, wherein the angle is less thanapproximately 75 degrees.
 8. The system of claim 1, wherein theinterstage seal comprises a first support feature configured to engagewith a second support feature disposed on one or more of the pluralityof first blade segments or the plurality of second blade segments toblock radial movement of the interstage seal toward an axial axis of themulti-stage turbine during installation or removal of the interstageseal, and to block circumferential movement of the interstage seal aboutthe axial axis during operation of the multi-stage turbine.
 9. Thesystem of claim 8, wherein the first support feature comprises a slotand the second support feature comprises a tab.
 10. The system of claim1, wherein the interstage seal comprises an axial end portion configuredto engage a wheel rim of the first wheel or the second wheel in a radialdirection during operation of the multi-stage turbine.
 11. The system ofclaim 1, wherein the interstage seal comprises a centrifugal sealconfigured to move toward the first turbine stage or the second turbinestage to block radial leakage when radial centrifugal forces aregenerated during operation of the multi-stage turbine.
 12. The system ofclaim 1, wherein the interstage seal comprises one or more seal teethconfigured to block interstage axial leakage between the first turbinestage and the second turbine stage.
 13. The system of claim 1, whereinthe interstage seal comprises one or more cooling passages configured todirect a cooling fluid flow toward the plurality of first blade segmentsor the plurality of second blade segments.
 14. The system of claim 1,comprising an interstage seal assembly disposed between the first andsecond turbine stages, wherein the interstage seal assembly comprises aplurality of interstage seals.
 15. A system, comprising: an interstageturbine seal configured to mount axially between first and secondturbine stages of a multi-stage turbine, wherein the interstage turbineseal comprises an inclined support rib configured to enable theinterstage turbine seal to pivot toward and away from an axial axis ofthe multi-stage turbine without removal of a first wheel of the firstturbine stage and a second wheel of the second turbine stage.
 16. Thesystem of claim 15, wherein the inclined support rib is oriented at anangle from an inner bridge portion of the interstage turbine seal,wherein the inclined support rib enables the interstage turbine seal topivot toward and away from the axial axis of the multi-stage turbine.17. The system of claim 16, wherein the interstage turbine sealcomprises a second recessed portion adjacent to the inclined supportrib, the second recessed portion is configured to receive a secondportion of the second wheel to enable pivotal motion of the interstageturbine seal toward and away from the axial axis, and a first recessedportion of the interstage turbine seal is configured to receive a firstportion of the first wheel while the interstage turbine seal is movedalong the axial axis toward the first turbine stage.
 18. The system ofclaim 15, wherein the interstage turbine seal comprises a first supportfeature configured to engage with a second support feature disposed on aportion of a blade segment coupled to the second wheel to block radialmovement of the interstage turbine seal toward the axial axis of themulti-stage turbine during installation or removal of the interstageturbine seal, and to block circumferential movement of the interstageturbine seal about the axial axis during operation of the multi-stageturbine.
 19. A method, comprising: positioning a first recessed portionof an interstage seal about a first wheel rim of a turbomachine;pivoting a second recessed portion of the interstage seal toward anaxial axis of the turbomachine; and moving the interstage seal along theaxial axis toward a second wheel rim of the turbomachine to position thesecond recessed portion about the second wheel rim.
 20. The method ofclaim 19, comprising engaging a first support feature disposed near thefirst recessed portion of the interstage seal with a second supportfeature disposed on a portion of a blade segment coupled to the firstwheel rim to block radial movement of the interstage seal toward theaxial axis of the turbomachine during installation or removal of theinterstage seal, and to block circumferential movement of the interstageseal about the axial axis during operation of the turbomachine.